immuno q8 - jcbc

[ArchivalUser]

A 35-year-old male presents to an infectious disease specialist with recurrent infections with encapsulated
bacterial organisms. The history indicates that these infections have become apparent in the last 6 months.
Laboratory findings indicates that the total immunoglobulin level exceeded 900 mg/dL with a low CH50 (hemolytic
complement) level. Which of the following is the correct diagnosis?
A. Acquired hypogammaglobulinemia (common variable hypogammaglobulinemia)
B. C3 deficiency
C. Hyper-IgM syndrome
D. Wiskott-Aldrich syndrome
E. X-linked infantile hypogammaglobulinemia

[ArchivalUser]

aa

[ArchivalUser]

B???

[ArchivalUser]

bbb

[ArchivalUser]

The correct answer is B. Individuals with C3 deficiency have an increased susceptibility to recurrent bacterial
infections, especially with encapsulated bacteria. This susceptibility illustrates the important role of C3 as an
opsonin. C3 deficiency is often not detected until later life.